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On 14 September 2015 at 4:50:45 AM Eastern standard time, the LIGO experiment detected the passage of \textbf{gravitational waves}. Scientists saw a very specific pattern of stretching and compression of space-time independently at the two locations of the experiment, one in Washington and the other in Louisiana. This amazing discovery has occurred Almost exactly 100 years after Albert Einstein published his General Theory of Relativy, and represents the last verification of this beautiful theory.  The cosmic storm that produced the gravitational waves was quite gnarly: Two black holes with a combined mass larger than 60 times the mass of our Sun and separated by just a few hundred kilometers spiraling towards each other at half the speed of light and then merging. The gravitational waves detected by LIGO were produced during the very last part of the in-spiraling process (last half second), when the two black holes were almost touching each other and the amount of energy deposited in gravitational waves was the largest. Looking at the received signal, scientist were able to determine how much energy was produced during the merger event. The initial masses of the two black holes were 36 and 29 times the mass of the Sun, but after the merger the mass of the newly formed black hole was only 62 solar masses. Where did the extra 3 solar masses go? The mass was converted into energy and used to produce the gravitational waves. Which means that the power emitted by the source for the very short duration of the event was larger than the integrated power emitted by all stars in the Universe! \textbf{This represents the most powerful event ever observed by humankind} (after the Big Bang).   The gravitational waves allowed the LIGO team to determine the distance of the merger, which turned out to have occurred 1.2 billion light years away. Why so far? The answer is that this kind of events are is  expected to be quite rare, so it is  statistically very unlikely to catch one nearby. We need to look at a large chunk of the Universe. This also explains why the LIGO experiment was so challenging: Initially the waves are pretty big and they distort space-time by a large amount, but by the time the waves reach Earth (in this case after a 1.2 billion years trip) their amplitude has decreased by a factor $1/d$. So LIGO had to measure a change in distance as small as 1/1000 the diameter of a proton to see the gravitational waves. So, how did the waves look like? Glassy and double-overhead!